he stole the forbidden Iwa technique that gave him the mouthes in his hands that let him put his KG into clay (Explosion release, like gari has and hanzo called him an explosion release user)and the one on his chest that turns him into a living bomb, so he has a KG he just stole what makes him a unique user of it.No he stole it
besides Deidara i'd agree, everyone else worked hard or stole their way to power they weren't born with it.Sasori
Kisame
Konan
Jiraiya
Tsunade
Orochimaru
Kakuzu
Deidara
You can see where this is going
also 3rd and 4th hokages/raikages, Shikamaru (inherited the shadow technique but his own intelligence is what lets him and his father use it so well) i guess Choji since he gained self confidence and got "strong"